Skewed X axis

Symptom

The perpendicularity of XY axes in a CoreXY layout relies on both the structure (XY joiners, bolt and nuts) and belt tensions. Sometimes builders find their X rail skewed as shown in the picture.

Solution

1. Loosen belts and the XY plane (Y linear blocks, Y rails, and sometimes the bolts from X rail to XY joiners too)

2. Fasten the bolts of X rail

3. Find parallelism of Y rails

   1. Push XY joiner against rear pulley housings and fasten bolts of Y linear blocks and the rear end of Y rails

   2. Gradually move the X gantry toward front end and fasten the bolts of Y rails

   3. Sometimes you'll have to loosen other bolts of Y rails you have fastened and repeat from step 2.

4. Tense the two belts last.